Pros and Cons of Various DC Distribution Architectures

Transcription

1 Pros and Cons of Various DC Distribution Architectures Source: Solar Powered Datacenter by Google Randy Malik Power Technology And Qualification IBM RTP Raleigh NC Rick Fishbune Power Technology And Qualification IBM Rochester, MN

2 Large Energy Consumers For 100 units of Coal (BTU) only 33 units available for use!!! Data Centers Consume 1.5% of total Electricity in USA 2 9/26/2008

3 High Energy Voltage Crisis Distribution for the Planet Bus Earth Sources: US EIA, US Census Bureau, (Patzek, 2007). 3 9/26/2008

4 Power and Cooling - the foundation to achieve business Objectives Desired Business Objectives Hardware & Software Critical Power & Cooling Investment is 2 4% of the total Capital Expenditure in the Datacenter Annual Energy Cost in a datacenter is approaching Capital Expenditure in a Datacenter Source IDC 4 9/26/2008

5 A Typical Tier 4 Datacenter Infrastructure 5 9/26/2008

6 Simplified High Voltage Diagram Distribution of a Tier 4 Bus Datacenter Free Air Raised Floor Battery Plant Row of IT Racks Free Air 208 V PDU ROW 1 Air Handler 480V AC 3 Phase 3 Phase AC UPS 1 STS 480 V ROW 2 480V AC 3 Phase 3 Phase AC UPS V PDU ROW 3 ROW 4 Air Handler ATS for Chillers 6 9/26/2008

7 Power Distribution in a Tier 4 Datacenter Efficiency From 480 Vac 12V DC : (.99x.989 x.90 ) = 88% AC Generators Raised Floor Data Processing Room 13.5kV 13.2KV/480 Transformer Double Conversion AC UPS 96.3% 3 Phase 480Vac PDU 480/208 V AC 99% Electronic Transfer 98.9% AC 208 V AC 3 Phase Switch 13.5 KV 13.2KV/480 Transformer Double Conversion AC UPS 3 Phase 480Vac PDU 480/208 V AC 98.9% AC V AC 3 Phase AC Generators 96.3% Battery Bank A row of Data Processing Racks 90% Best efficiency for 12V AC DC Rectifier 7 9/26/2008

8 48V or 400V DC Distribution Concept for Tier 4 Datacenter 13.5KV 13.5KV AC Generators 13.2KV/488 Vac Transformer 13.2KV/488 Vac Transformer Best Possible Efficiency (Non-isolated) =.98 x.97 = 95% Best Possible Efficiency (Isolated) =.96 x.97) = 93% 480V AC 3 Phase Neutral 480V AC 3 Phase AC DC Rectifiers in parallel 98% AC DC Rectifiers in parallel DC Bus 1 ( 400V DC or 48V DC) 400V DC Distribution Issues: 1. Safety Concern 2. Customer Perception 3. Certified connectors are not available DC Bus 2 ( 400V DC or 48V DC) Raised Floor AC Generators Neutral 98% Battery Bank 97% 400V - 12V Unregulated Rack 8 9/26/2008

9 Solar Powered Datacenter with DC Distribution Estimated Savings in Power = 5 MW Estimated Savings in Electric Bill = 5 M Dollars/Year! DC DC Converter 13.2KV AC Generators 13.2KV/488 Vac Transformer 480V AC 3 Phase Neutral AC DC Rectifiers in parallel 98% X DC Bus 1 ( 400V DC or 48V DC) Raised Floor 480V AC 3 Phase 13.2KV 13.2KV/488 Vac Transformer AC DC Rectifiers in parallel X DC Bus 2 ( 400V DC or 48V DC) AC Generators Neutral 98% Battery Bank 97% 400V - 12V Unregulated Rack 9 9/26/2008

10 DC Distribution in a Datacenter IT Racks PDU UPS 208 /120V 480V AC UPS 6.5% PDU 2.5% 208 /120V 400V DC or 48V DC Rectifiers Battery Plant 10 9/26/2008

11 X Series Power Supply Efficiency 100% Load Maximum Output Power (W) % 75% 80% 85% 90% 95% Multiple Output Power Supplies 11 9/26/2008

12 480Vac High Plug Voltage to Processor Distribution Efficiency for Bus a typical Datacenter Overall Efficiency and Normalized Power UPS System Raised Floor Transformer Distribution AC DC Power Supply DC DC Regulator Processors, Memory, ICs) AC Distribution 480V AC 400 VDC 480V AC 400V AC 208V AC : 3 Phase Data Center Distribution 208Vac 12V DC 12 VDC 1V DC 1V to Heat Typical Efficiency Normalized Power Best in Class Efficiency Normalized Power % % Best Efficiency Technology limit 85.10% Normalized Power V DC Or 48V NA NA Distribution Efficiency AC DC Rectifiers 12 VDC 1VDC Or 5Vdc 1V 1V to Heat Efficiency :Isolated 85.25% Normalized Power Efficiency No Isolated Rectifiers % Normalized Power /26/2008

13 Increase in Compute Capacity in a Datacenter Power Consumption in a Typical Datacenter Compute Capacity Increase due to DC Distribution and Power System Efficiency Increase 23% 10% 51% 38% 1% 38% 1% 38% IT Power System Cooling Lighting IT Power System Cooling Lighting 13 9/26/2008

14 Power Saved High by using Voltage DC Distribution and Bus Efficient Power Supplies Power Saved = 0.464W to power 1 Watt Load Total Electrical Utility Bill savings = Dollars/year for 1 MW IT load AC Distribution DC Distribution Power Dissipated (Watt) W 0 Typical Best in Class Best Possible Isolated Nonisolated DC - DC AC - DC Distribution PDU UPS 14 9/26/2008

15 N+1 vs. N+N Downtime (seconds) in a year 60 ( MTTR = 48 Hours, MTBF = 250K Hours Downtime in Seconds) Downtime Number of rectifiers Availability (A) = 1 MTTR/MTBF for a single Rectifier Availability with N +1 Rectifiers in parallel = A n+1 + (n+1) x A n x (1-A) 15 9/26/2008

16 N+1 vs. N+N Service Requirement Frequency 0.25% 0.20% Service Frequency 0.15% 0.10% 0.05% 0.00% Number of rectifiers Service Frequency Service Frequency = 1 A n+1 MTTR = 48 Hours, MTBF = 250K Hours 16 9/26/2008

17 Comparison of Different Power Architectures Typical AC AC Best in Class AC Best Possible Isolated 48V Isolated / Nonisolated 400V DC DC Redundancy At Server or Rack Level At Server or Rack Level At Server or Rack level Central Rectifier Central Rectifier Safety Concern No Concern No Concern No Concern No Concern Great Concern Industry Standard Components Customer Acceptance Yes Yes Yes Yes No High High High Acceptable Very Low Battery Issue NA NA NA Low Failure High Failure due to cells in series AC UPS required Yes Yes Yes No No Neutral availability on Raised Floor NA NA NA No Concern Not Required /Required Repair Frequency High High High Low Low Overall Cost Low at Power Supply level but high at Datacenter level Low at Power Supply level but high at Datacenter level Low at Power Supply level but high at Datacenter level Low at Power Supply level but high at Datacenter level High at Power Supply level but low at Datacenter level 17 9/26/2008

18 Minimum Power Point Tracking Tool UPS Air Handler Humidifier Rectifiers CRAC MPP Tracking Tool Server Racks 18 9/26/2008

19 Additional Energy Saving Techniques % Energy Savings Low power Processors 29% 3% 16% Power Management Server Virtualization 18% VFD Cooling 11% 23% Supplemental Cooling Cooling units work as a team Source: Emerson Network Power White Paper 19 9/26/2008

20 Conclusion Lower Overall Cost No Step Down Transformers No AC UPS Less Feeds from Wall Higher Reliability, Availability, and Scalability Higher overall Efficiency DC Distribution best suited for Solar Array Power Less Repair frequency 20 9/26/2008